Method for the wet treatment of laundry

ABSTRACT

In tunnel-type washing machines ( 10 ) for commercial laundries, the main-wash liquid is heated by steam in particular. This means a steam-generating system is required in the laundry. The invention makes provision for the main-wash liquid to be heated up by means of a flow heater, preferably a heating device ( 26 ) which has a gas burner ( 28 ). As a result, the tunnel-type washing machine ( 10 ) can also be used in laundries which do not have a steam generating system. The invention also makes provision for the gas burner ( 28 ) of the flow heater to be operated continuously since treatment liquid which is required for other purposes, preferably treatment liquid which is temporarily stored in a storage tank ( 31 ), is heated up after the main-wash liquid is heated up. Uninterrupted, economical operation of the gas burner ( 28 ) is ensured as a result.

STATEMENT OF RELATED APPLICATIONS

This patent applications is based on and claims the benefit under 35 USC 119 of German Patent Application No. 10 2007 051 083.9 having a filing date of 24 Oct. 2007, which is incorporated herein in its entirety by this reference.

BACKGROUND OF THE INVENTION

1. Technical Field

The invention relates to a method for the wet-treatment of laundry, the laundry being at least washed in a drum which can be driven in rotation using a heated-up treatment liquid, and a method for the wet-treatment of laundry, the laundry being at least washed in a drum which can be driven in rotation using a warmed treatment liquid.

2. Related Art

Various washing machines are used in commercial laundries for the wet-treatment of laundry of any type. In this case, the washing machines are firstly tunnel-type washing machines with a plurality of successive chambers in a single drum which can be driven in rotation. In the tunnel-type washing machine, the laundry is at least washed by a pre-wash operation and a main-wash operation. However, the tunnel-type washing machine can also serve to wash and rinse and possibly also post-treat, for example finish, the laundry. Secondly, so-called spin dryers are used in commercial laundries, in which spin dryers the laundry is washed, rinsed and spun-dry in a drum which can be driven in rotation and has only one chamber.

Washing is performed with a treatment liquid which is heated up at least for main-wash purposes, the laundry to be washed also being heated to the temperature of the treatment liquid. In known washing machines, the treatment liquid is heated using steam. This means a steam-generating device is required in the laundry, and this entails high investment costs.

BRIEF SUMMARY OF THE INVENTION

The invention is then based on the object of providing methods for the wet-treatment of laundry, which methods permit the treatment liquid to be heated up using simple means and permit economical operation.

A method for achieving this object is a method for the wet-treatment of laundry, the laundry being at least washed in a drum which can be driven in rotation using a heated-up treatment liquid, characterized in that the treatment liquid is heated up by at least one heating device. According to the said method, provision is made for the treatment liquid to be warmed by at least one heating device. As a result, steam is no longer required to heat the treatment liquid. On account of the method according to the invention, complicated steam generation in the laundry can be dispensed with.

The heating device is preferably a heating device which is operated with fossil fuels, such as gas or oil in particular. A heating device of this type requires only a gas and/or oil burner which continuously warms the treatment liquid which is conducted through heating coils in the burner in accordance with the heat-exchanger principle. A heating device of this type is very simple. Above all, a heating device of this type can be used as an alternative or in addition to parallel operation for other purposes. In one preferred refinement of the method, the heating device is a flow heater which continuously warms treatment liquid which is pumped in circulation continually through the heating device. The treatment liquid warmed by the heating device can then be circulated through the washing machine. This is performed by continual pumping of the treatment liquid which is warmed by the heating device and is cooled down as the laundry is warmed up as the said treatment liquid is conducted through the washing machine. In particular, treatment liquid which is warmed by the heating device is pumped in circulation through at least one chamber of the tunnel-type washing machine. Circulation of this type can be realized in a simple manner and leads to continuous raising of the temperature of the treatment liquid and the laundry through which the treatment liquid is pumped in circulation.

In a further preferred refinement of the method, provision is made to operate the heating device continuously, that is to say in a substantially uninterrupted manner. In this case, the required heating energy is controlled by the quantity of gas or oil supplied to the heating device per unit time. However, the heating device is operated substantially continuously, specifically fired by oil or gas. The heating device is switched off only in the event of relatively long unpredicted interruptions in operation or in the event of a relatively long-lasting interruption in the washing process.

The invention also proposes using energy which is required for constant operation of the heating device, but is not currently required to heat up the treatment liquid for washing the laundry in the drum, for other purposes. The heating device can then continue to be operated even though treatment liquid for washing the laundry does not currently have to be heated up. In this way, operation of the heating device is maintained even if treatment liquid for washing the laundry temporarily does not have to be heated up. The energy which is then further generated by the heating device is preferably used for other purposes or to warm or heat up treatment liquid which will be required later.

A further method for achieving the object cited in the introduction, this method possibly also being a preferred development of the method described above, is a method for the wet-treatment of laundry, the laundry being at least washed in a drum which can be driven in rotation using a warmed treatment liquid, characterized in that treatment liquid for the laundry in the drum or for other purposes is heated up or warmed alternately by a heating device. According to the said method, provision is made for treatment liquid for the laundry to be washed in the drum or for other purposes to be warmed alternately by the at least one heating device. As a result, the at least one heating device can be operated in an uninterrupted manner over relatively long periods of time, for which reason only the heating power may be changed in order to adapt to the current conditions. This method is preferably suitable for gas- and/or oil-operated heating devices which warm or heat the treatment liquid in accordance with the heat-exchanger principle. The cost-effectiveness of such heating devices is improved when they are operated over a relatively long time, specifically preferably with no interruptions in operation or as few interruptions in operation as possible.

In one preferred refinement of the method, treatment liquid for washing the items of laundry in the drum is first heated by the at least one heating device. Liquid, in particular treatment liquid, which is temporarily stored in at least one storage tank during further operation of the at least one heating device, is warmed only when the treatment liquid and the laundry have reached the intended temperature, and further heating-up of the treatment liquid for washing the respective batch of laundry is no longer required. The at least one storage tank therefore serves to buffer-store the thermal energy which continues to be generated by the heating device between washing operations for successive batches of laundry. In the period between heating-up of the treatment liquid of successive batches of laundry, the at least one heating device can continue to be operated, to be precise possibly with a reduced or minimum heating power. However, according to the invention, the at least one heating device does not have to be switched off between heating-up of the treatment liquid for successive batches of laundry. Uneconomical interruptions in operation of the at least one heating device can thus be reduced to a minimum.

According to one preferred refinement of the method, provision is made for the warmed liquid or treatment liquid to be used in at least one storage tank for washing the laundry into the drum and/or to prepare the pre-heated treatment liquid for washing the next batch of laundry. This treatment liquid then needs to be only slightly heated up, this reducing the cycle time of the washing machine.

The invention can be used in a particularly advantageous manner to heat up treatment liquid which serves for main washing of the laundry, specifically main-wash liquid. Warming up or heating the main-wash liquid to the temperature required for the main-wash operation by at least one gas- and/or oil-heated heating device has proven particularly cost-effective.

BRIEF SUMMARY OF THE FIGURES

Preferred exemplary embodiments of the invention are explained in greater detail below with reference to the drawing, in which:

FIG. 1 shows a schematic view of a tunnel-type washing machine with at least a pre-wash zone, main-wash zone and a rinse zone.

FIG. 2 shows a schematic view of a tunnel-type washing machine with a pre-wash zone and a main-wash zone according to a second exemplary embodiment of the invention.

FIG. 3 shows the tunnel-type washing machine according to FIG. 2 having a plurality of storage tanks according to a third exemplary embodiment of the invention.

FIG. 4 shows a schematic view of a spin dryer according to a fourth exemplary embodiment of the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The figures show the various washing machines for commercial laundries, with which washing machines the method according to the invention can be carried out. However, the invention is not restricted to the washing machines shown. Rather, the method according to the invention is suitable for all types of washing machines for, in particular, commercial laundries. The washing machines serve to wash laundry of all types, in particular flat laundry such as table linen, bed linen and hand towels, any items of clothing, mats and the like. These articles may include both white and coloured laundry.

FIG. 1 shows a tunnel-type washing machine 10 for washing, specifically pre-washing and main-washing, and for rinsing the laundry. The tunnel-type washing machine 10 has a cylindrical drum 12 which can be driven in rotation about a horizontal rotation axis 11. A plurality of chambers 13, 14 and 15 which follow one another along the rotation axis 11 are formed in the drum 12. The tunnel-type washing machine 10 shown has twelve chambers 13, 14 and 15. However, the invention is not restricted to this. Rather, the invention is suitable for tunnel-type washing machines 10 with any desired number of chambers 13, 14 and 15.

An inlet funnel 16, by way of which the laundry to be washed enters the drum 12, is located at the start of the drum 12 upstream of the tunnel-type washing machine 10. A discharge funnel 18 is provided at that end of the drum 12 which is at the rear as seen in the treatment direction 17. The washed and rinsed laundry leaves the tunnel-type washing machine 10 via the discharge funnel 18.

A water-removal device 19 is provided downstream of the tunnel-type washing machine 10. The said water-removal device may be a centrifuge or a water-removal press. The laundry passes from the drum 12 of the tunnel-type washing machine 10, via the discharge funnel 18, into the water-removal device 19. The water-removal device 19 serves to remove a large portion of the treatment liquid, in particular bound liquor, from the laundry.

The tunnel-type washing machine 10 shown in FIG. 1 has a pre-wash zone 20, which is followed in the treatment direction 17 by a main-wash zone 21 and, downstream of this, a rinse zone 22. The laundry may be subjected to post-treatment, for example finishing, in the rinse zone 22. Some of the chambers 13, 14 and 15 of the pre-wash zone 20, the main-wash zone 21 and the rinse zone 22 have associated outer drums 23, 24 and 25. These outer drums serve to supply treatment liquid to the respective chamber and to drain treatment liquid from the respective chamber.

The tunnel-type washing machine 10 has an associated heating device 26. The said heating device is a gas-operated heating device 26 with a gas burner 28. However, heating devices 26 which are operated with other fossil fuels, for example oil, are also feasible. The heating device 26 also has a heat exchanger 27. The heating device 26 therefore constitutes a flow heater. The heat exchanger 27 can be configured in any desired manner. In FIG. 1, the heat exchanger 27 is symbolically illustrated as a helical tube. The helical tubes or heat exchangers 27 are heated by the gas burner 28 of the heating device 26. The heating device 26, that is to say the gas burner 28 and the heat exchanger 27, are arranged as a unit as close as possible next to the tunnel-type washing machine 10, so that only short tube lines are required. However, it is also feasible to arrange the heating device 26 closely next to the drum 12 and thus integrate it in the frame of the tunnel-type washing machine 10.

In the exemplary embodiment shown, the heating device 26 is intended to heat up the main-wash liquid and the laundry contained therein. To this end, a return line 29 is passed from the outer drum 23 of the last chamber 13 of the pre-wash zone 20 to the entry of the heat exchanger 27 of the heating device 26 in the exemplary embodiment shown. The warmed treatment liquid which leaves the heat exchanger 27 is returned to the outer drum 23 of the last chamber 13 of the pre-wash zone 20 via an inflow line 30. Treatment liquid, to be precise main-wash liquid in this case, which is warmed by the heating device 26 is therefore conducted in circulation through the last chamber 13 of the pre-wash zone 20, which chamber is provided with the outer drum 23. During circulation of the main-wash liquid and the gradual warming of the said main-wash liquid which takes place in the process, together with the laundry contained in the chamber 13, initial main-washing takes place as early as in the last chamber 13 of the pre-wash zone 20 because the drum 12 continues to be driven in circulation, preferably continuously, as the main-wash liquid is circulated and warmed up.

The main-wash liquid warmed by the heating device 26 is introduced into the bottom of the outer drum 23 by the inflow line 13. Similarly, cooled main-wash liquid is returned to the heating device 26 at the bottom of the opposite end region, which is at the front in the treatment direction 17, from the outer drum 23 via the return line 29. As an alternative, it is feasible to introduce the warmed main-wash liquid into the top of the outer drum 23. The inflow line 30 would then issue into the outer drum 23 of the last chamber 13 of the pre-wash zone 20 from above. It is also feasible to use the outer drum 24 of the first chamber 14 of the main-wash zone 21 to warm up the main-wash liquid. In this case, return lines 29 are associated with the outer drum 23 of the last chamber 13 of the pre-wash zone 20 and the outer drum 24 of the first chamber 14 of the main-wash zone 21, the said return lines leading to the heating device 26. Similarly, two inflow lines 30 then run from the heating device 26 to the outer drums 23 and 24. The heating device 26 then supplies the heated main-wash liquid to two outer drums 23 and 24. However, it is also feasible for each outer drum 23 and 24 to have its own associated heating device 26 with in each case a return line 29 and an inflow line 30. In this case, two circuits and two heating devices 26 for warming the main-wash liquid are present in the last chamber 13 of the pre-wash zone 20 and the first chamber of the main-wash zone 21.

The tunnel-type washing machine 10 shown has a storage tank 31. A feed line 32 arriving from the water-removal device 19 is led to the storage tank 31. The liquid, in particular rinse liquid, which is removed from the laundry by the water-removal device 19 enters the storage tank 31 through the feed line 32. In the exemplary embodiment shown, a further feed line 33 to the storage tank 31 is provided, which feed line starts from the first chamber 15 of the rinse zone 22, in particular the first drum 25 of the rinse zone 22. The said further feed line may be an overflow in the outer drum 25 or the first chamber 15 of the rinse zone 22. A corresponding quantity of liquid which is temporarily stored in the storage tank 31 can be passed to the start of the tunnel-type washing machine 10, specifically to the inlet funnel 16, from the storage tank 33 via an outflow line 34 as required. A second outflow line 35 leads from the storage tank 31 either to the last chamber 13 of the pre-wash zone 20 or to the first chamber 14 of the main-wash zone 21.

Heated treatment liquid can be supplied from the heating device 26 to the storage tank 31 via an inflow line 36. Furthermore, a return line 37 leads from the storage tank 31 to the start of the heating device 26. A second circuit for treatment liquid which is heated by the heating device 26 is formed between the heating device 26 and the storage tank 31 as a result.

The tunnel-type washing machine 10 can have one or else a plurality of additional heating devices 26 which serve to warm up treatment liquid at the start of the rinse zone 22 or in the course of the rinse zone and to warm up the laundry in the said zones. An inflow line and a return line from the respective heating device can accordingly be associated with the outer drum 24 at the end of the main-wash zone or with the outer drum 25 at the start of the rinse zone 22, however also with an outer drum 25 of the penultimate chamber 15 of the rinse zone 22 or the last chamber 15 of the rinse zone 22. However, it is also feasible to supply a plurality of outer drums 23, 24 and/or 25 with heated treatment liquid in circulation alternately from a single common heating device 26.

The method according to the invention is explained below in conjunction with the tunnel-type washing machine 10 shown in FIG. 1:

Treatment liquid which is provided for the main-wash operation in the main-wash zone 21 is initially continuously warmed by the heating device 26. The main-wash liquid is therefore continuously warmed up as the drum 12 continues to be driven in rotation. In the process, the laundry in the last chamber 13 of the pre-wash zone 20 is also gradually warmed. The main-wash liquid is warmed in accordance with the continuous-flow principle by constant circulation of the main-wash liquid conducted through the heat exchanger 27 of the heating device 26 by pumping. In the process, the main-wash liquid is circulated from the outer drum 23 of the last chamber 13 of the pre-wash zone 20, through the inflow line 30, the heat exchanger 27 of the heating device 26 and the return line 29, back to the outer drum 23. The warmed-up main-wash liquid is constantly circulated by pumping until the main-wash liquid upstream of the main-wash zone 21 and the laundry in the main-wash liquid have reached a prespecified main-wash temperature.

However, once the main-wash liquid and the laundry contained therein have reached the prespecified temperature, the heating device 26 continues to be operated according to the invention. The treatment liquid in the storage tank 31 is heated by the heating device 26 in the process. To this end, the treatment liquid in the storage tank 31 is likewise pumped in circulation from the storage tank 31, via the return line 37, through the heat exchanger 27 of the heating device 26 and through the inflow line 36, back to the storage tank 31. The treatment liquid in the storage tank 31 which is continuously warmed in accordance with the continuous-flow principle in this way is used at the specified time to wash a next batch of laundry into the tunnel-type washing machine 10 and/or to fill the last chamber 13 of the pre-wash zone 20 or the first chamber 14 of the main-wash zone 21 with treatment liquid.

Since the treatment liquid in the storage tank 31 is warmed at least at the end of the pre-wash zone 20 between successive phases of warming-up of the main-wash liquid of successive batches of laundry, continuous operation of the heating device 26, in particular of the gas burner 28 of the said heating device, is possible. In this case, the heating power of the gas burner 28 may be reduced to a minimum, so that the treatment liquid in the storage tank 31 can be heated-up with a reduced heating power of the gas burner 28 between successive phases of warming of the main-wash liquid. The heating power of the gas burner 28 is designed such that the gas burner 28 can be operated continuously in the normal case. Operation of gas burner 28 is interrupted only in exceptional circumstances, for example during operating breaks in the tunnel-type washing machine 10.

It is also feasible for the tunnel-type washing machine 10 to have a plurality of associated storage tanks 31. In this case, the treatment liquid in one of the storage tanks 31 is selectively heated up when no main-wash liquid is to be heated up by the heating device 26.

If the tunnel-type washing machine 10 has a plurality of heating devices 26, all the heating devices 26 are preferably operated continuously, these heating devices 26 warming treatment liquid in one storage tank 31 or else plurality of storage tanks 31 when no rinse liquid or any other treatment liquid in the tunnel-type washing machine 10 is to be heated up, in order to thus temporarily store or buffer-store the liquid warmed by the continuously operated heating devices.

In cases where not only the main-wash liquid, but also rinse liquid or water-removal liquid, is to be continuously warmed by the heating device 26, it is also feasible to use the same heating device 26 to warm up or heat up the main-wash liquid, the rinse liquid and possibly the finishing liquid in succession. In such a case, it may become unnecessary to temporarily store the treatment liquid in at least one storage tank 31 for buffer-storing the energy generated by the gas burner 28.

FIG. 2 shows a tunnel-type washing machine 38 which serves only to wash, specifically to pre-wash and main-wash, the laundry. The laundry is rinsed in a water-removal device 39 which is arranged downstream of the tunnel-type washing machine 38. The water-removal device 39 may be a centrifuge or a press which rinses the laundry and then removes water from it. The tunnel-type washing machine 38 also has a cylindrical drum 41 which can be driven in rotation about a horizontal rotation axis 40. A plurality of chambers 42, 43 which follow one another along the rotation axis 40 are arranged in the drum 41. The tunnel-type washing machine shown has five chambers 42, 43. However, the invention is not restricted to this.

An inflow funnel 44, via which the laundry to be washed enters the drum 41, is located at the start of the drum 41 upstream of the tunnel-type washing machine 38. A discharge funnel 45 is provided at that end of the drum 41 which is at the rear as seen in the treatment direction 17. The washed laundry leaves the tunnel-type washing machine 38 via this discharge funnel.

The tunnel-type washing machine 38 shown in FIG. 2 has only a pre-wash zone 46 and a main-wash zone 47 which follows in the treatment direction 17. The last chamber 42 of the pre-wash zone 46 has an associated stationary outer drum 48. The last chamber 43 of the main-wash zone 47 has a further outer drum 49. Dirty pre-wash water can be drained from the last chamber 42 of the pre-wash zone 46 via the outer drum 48, before main-wash liquid is conducted into the drum 41 into this chamber 42 via the outer drum 48. Similarly, the main-wash liquid can be discharged via the last outer drum 49.

The tunnel-type washing machine 38 has an associated heating device 50. This heating device can be arranged next to the tunnel-type washing machine 38 or else be integrated in the said tunnel-type washing machine. The heating device 50 is in the form of a flow heater, for which reason it has a gas burner 51 and a heat exchanger 52. The treatment liquid which is to be warmed up is continuously pumped through the heat exchanger 52 which is illustrated symbolically as a helical tube in FIG. 3. In the exemplary embodiment shown, the treatment liquid is main-wash liquid. Warmed main-wash liquid is conducted from the heat exchanger 52 of the heating device 50, via an inflow line 53, into the lower region of the outer drum 48 of the last chamber 42 of the pre-wash zone 46. However, as an alternative, warmed treatment liquid can also be conducted into the chamber 42 from above. Cooler or cooled main-wash liquid is conducted back to the start of the heat exchanger 52 of the heating device 50 from the outer drum 48 of the last chamber 42 of the pre-wash zone 46 via a return line 54. The outer drum 48 of the last chamber 42 of the pre-wash zone 46, the inflow line 53, the return line 54 and the heat exchanger 52 therefore form a closed circuit for the main-wash liquid which is warmed by the gas burner 51.

The tunnel-type washing machine 38 has a storage tank 55. The storage tank 55 accommodates the liquid separated off from the laundry by the water-removal device 39 during the water-removal operation, the said liquid being rinse liquid. To this end, a feed line 56 leads from the water-removal device 39 to the storage tank 55. The liquid stored in the storage tank 55 can be fed from the storage tank 55, via a discharge line 57, to the start of the drum 41, to the inlet funnel 44 in the exemplary embodiment shown. As an alternative, treatment liquid can be supplied from the storage tank 55 to the last chamber 42 of the pre-wash zone 46 via an outflow line 58. For example, at least a portion of the main-wash liquid, to be precise as already pre-heated main-wash liquid, can be supplied from the storage tank 55 through the outflow line 58 after draining of the pre-wash liquid from the outer drum 48 of the chamber 42.

A further inflow line 59 leads from the heat exchanger 52 of the heating device 50 to the storage tank 55. Furthermore, a return line 60 returns to the heat exchanger 52 of the heating device 50 from the storage tank 55.

The tunnel-type washing machine 38 likewise operates in accordance with the method according to the invention, to be precise in principle as described in conjunction with the tunnel-type washing machine 10 of the exemplary embodiment of FIG. 1. Accordingly, the heating device 50 is also operated continuously, or at least mainly continuously. The main-wash liquid in the last chamber 42 of the pre-wash zone 46 is initially continuously warmed since main-wash liquid which is warmed by the heating device 50 is continually pumped through the outer drum 48 and the last chamber 42 of the pre-wash zone 46 via the inflow line 53 and the return line 54. The main-wash liquid warmed in the heating device 50 is constantly circulated in order to warm up the main-wash liquid and the laundry contained in the chamber 42 to the main-wash temperature in the last chamber 42 of the pre-wash zone 46. In this case, the main-wash liquid is continuously warmed by the heating device 50, so that the heating device 50—like all the other heating devices—constitutes a flow heater.

When the main-wash liquid and the laundry contained therein are at the intended main-wash temperature, the heating device 50 continues to be operated until the main-wash liquid for the next batch of laundry is heated, this possibly being done with a restricted heating power of the gas burner 51. During this further operation of the heating device 50, the treatment liquid in the storage tank 55 is warmed, as it were, as a buffer store for storing the energy generated by the gas burner 51 between two successive batches of laundry. To this end, the treatment liquid in the storage tank 55 is continuously circulated from the heat exchanger 52, through the inflow line 59, to the storage tank 55 and back to the heat exchanger 52 of the heating device 50 via the return line 60. This second treatment-liquid circuit of the heating device 50 is operated when no main-wash liquid is warmed in the last chamber 42 of the pre-wash zone 46 between two successive batches of laundry. The warmed treatment liquid in the temporary storage means 50 can be conducted either to the start of the tunnel-type washing machine 38 via the outflow line 57 and there be used to wash-in the laundry to be washed or it serves to fill the outer drum 48 of the last chamber 42 of the pre-wash zone 46 with pre-heated main-wash liquid. On account of the pre-heating in the storage tank 55, this main-wash liquid is at a temperature which corresponds to the main-wash temperature, but may also be below this.

The exemplary embodiment of FIG. 3 differs from the exemplary embodiment of FIG. 2 only in that the tunnel-type washing machine 38 and the water-removal device 39 have an associated second storage tank 61. Otherwise, the tunnel-type washing machine 38, the water-removal device 39 and the heating device 50 correspond to the exemplary embodiment of FIG. 2, for which reason identical reference numerals are used for identical parts.

The treatment liquid which is separated off from the laundry by the water-removal device 39 and which contains, in particular, a large portion of the liquor bound in the laundry, in particular rinse liquid, is supplied either to the storage tank 55 or 61 via a branched feed line 56. To this end, the feed line has two parallel feed line sections 62 and 63 which lead firstly to the storage tank 55 and secondly to the storage tank 61. By virtue of valves in the feed line sections 62 and 63, it is possible to determine which of the two storage tanks 55 or 61 the liquid, in particular rinse liquid, is conducted into from the water-removal device 39.

Only one discharge line 64 to the discharge line 57 leads from the additional storage tank 61 to the inlet funnel 44 upstream of the tunnel-type washing machine 38.

The cold water-removal liquid, which originates from the water-removal device 39 and is preferably at approximately room temperature, is warmed by the heating device 50 in the storage tank 55, as described in conjunction with FIG. 2, specifically between heating-up of main-wash liquid between two successive batches of laundry. In contrast, the water-removal liquid in the storage tank 61 cannot be pre-heated by the heating device 50. Therefore, the storage tank 55 contains warmer treatment liquid, in particular water-removal liquid, than storage tank 61. As a result, the inflow funnel 44 at the start of the tunnel-type washing machine 38 can be supplied with relatively cold treatment liquid from the storage tank 61 and pre-heated treatment liquid from the storage tank 55. The treatment liquid from the two storage tanks 55 and 61 can be mixed by virtue of corresponding valves downstream of the storage tanks 55 and 61, in order to provide the treatment liquid for washing the laundry into the tunnel-type washing machine 38 with a desired temperature, in particular a lower temperature than the treatment liquid in the storage tank 55 heated up by the heating device 50.

In the exemplary embodiment of FIG. 4, the method according to the invention is described in conjunction with a washer-dryer 65. The washer-dryer 65 has a drum 66 which can be driven in rotation and has a single chamber. The drum 66 is surrounded by a stationary outer drum 70 with a common loading and unloading opening. The outer drum 70, together with the rotatable drum 66 mounted therein, can be pivoted about an axis which runs transverse to the rotation axis of the drum during treatment of the laundry. The laundry is the subjected to pre-washing, main-washing, rinsing and water-removal in the single chamber of the drum 66.

The washer-dryer 65 has its own associated heating device 67 which, like the heating devices described above, has a gas burner 68 and a heat exchanger 69.

An inflow line 71 for treatment liquid which is warmed by the heating device 67 is led to the stationary outer drum 70 of the washer-dryer 65. Cooled treatment liquid, in particular main-wash liquid, is returned from the outer drum 70 of the washer-dryer 65 to the start of the heat exchanger 69 of the heating device 67 via a return line 72.

The washer-dryer 65 shown here has two associated storage tanks 73, 74. The storage tanks 73, 74 accommodate the treatment liquid, in particular water-removal liquid which is produced when the laundry is spun in the washer-dryer 65. The water-removal liquid, this possibly also being rinse liquid, can be supplied selectively to one or the other storage tank 73 or 74 via a feed line 75 with two feed line sections 76, 77.

An inflow line 78 and a return line 79 are associated with one of the storage tanks, specifically the storage tank 74. This creates a second circuit which is connected to the storage tank 74 for treatment liquid which is pre-heated or heated by the heating device 67.

An alternative exemplary embodiment is feasible, in which the washer-dryer 65 has more than two associated storage tanks 73 and 74, to be precise for treatment liquid which is intended for coloured laundry on the one hand and for white laundry on the other. In this case, the apparatus can have two storage tanks 73, 74 for coloured laundry and two storage tanks 73, 74 for white laundry. This alternative also applies to the three exemplary embodiments of the invention described above.

According to a further alternative of the exemplary embodiment of FIG. 4, the storage tank 73 can be dispensed with, so that the washer-dryer 65 has only one associated storage tank 74, it being possible for the water-removal liquid contained in the said storage tank to be preheated or heated up by the heating device 67, to be precise up to the temperature of the main-wash liquid. As an alternative, the washer-dryer 65 can have two associated storage tanks 74, to be precise for coloured laundry and for white laundry. In this case, the treatment liquid in the two storage containers 74 (for the coloured laundry and the white laundry) can be heated up together or alternately by the heating device 67.

The method according to the invention proceeds with the washer-dryer 65 shown in FIG. 4, in principle, in exactly the same way as with the tunnel-type washing machine 38 of the exemplary embodiment of FIG. 3.

In the case of the washer-dryer 65, the pre-washed liquid is first drained from the drum 66 and the drum 66 is filled with main-wash liquid, to be precise possibly from the storage tank 74 which contains treatment liquid which is pre-heated by the heating device 67, after pre-washing. This treatment liquid does not yet all have to be at the temperature of the main-wash liquid. After the drum 66 of the washer-dryer 65 is filled with main-wash liquid, main-wash liquid which is heated by the heating device 67 by virtue of a continuous-flow method is pumped in circulation through the drum 66, that is to say is circulated. In the process, the treatment liquid is heated to the intended temperature and at the same time the laundry contained in the treatment liquid is warmed up to the main-wash temperature.

After the main-wash liquid of the laundry in the drum 66 has reached the intended main-wash temperature, circulation of the main-wash liquid through the drum 66 is interrupted. However, the heating device 67 continues to be operated, it being possible to reduce the heating power of the gas burner 68. Until the main-wash liquid for the next batch of laundry in the washer-dryer 65 is warmed, the treatment liquid in the storage container 74 is circulated through the inflow line 78, which is connected to the storage tank 74, and the return line 79 and in the process continuously warmed by the heat exchanger 69 of the heating device 67. This continues until the main-wash liquid for the next batch of laundry is to be warmed in the washer-dryer 65.

Therefore, even in the exemplary embodiment of FIG. 4, the gas burner 68 of the heating device 67 is operated in an uninterrupted manner as long as successive batches of laundry are to be treated in the washer-dryer 65. On account of the continuous operation of the heating device 67, the gas burner 68 does not have to be switched off in the phases in which no main-wash liquid is to be heated, that is to say between successive batches of laundry which are to be treated in the washer-dryer 65. At most, the heating power of the gas burner 68 is restricted between two successive batches of laundry. The gas burner 68 can therefore be continuously operated by treatment liquid in the storage container 74 being warmed between successive batches of laundry and then being used for filling the drum 66 of the washer-dryer 65 with new main-wash liquid, but also for washing the laundry into the drum 66 of the washer-dryer 65.

The invention is not restricted to the heating devices described above. The invention can also be realized with other flow heaters. It is also feasible, within the scope of the invention, to use burners which operate with other fossil fuels, for example oil, or else burners which can be selectively operated with various fossil fuels, in place of the gas burners.

LIST OF REFERENCE SYMBOLS

-   10 Tunnel-type washing machine -   11 Rotation axis -   12 Drum -   13 Chamber -   14 Chamber -   15 Chamber -   16 Inlet funnel -   17 Treatment device -   18 Discharge funnel -   19 Water-removal device -   20 Pre-wash zone -   21 Main-wash zone -   22 Rinse zone -   23 Outer drum -   24 Outer drum -   25 Outer drum -   26 Heating device -   27 Heat exchanger -   28 Gas burner -   29 Return line -   30 Inflow line -   31 Storage tank -   32 Feed line -   33 Feed line -   34 Outflow line -   35 Outflow line -   36 Inflow line -   37 Return line -   38 Tunnel-type washing machine -   39 Water-removal device -   40 Rotation axis -   41 Drum -   42 Chamber -   43 Chamber -   44 Inlet funnel -   45 Discharge funnel -   46 Pre-wash zone -   47 Main-wash zone -   48 Outer drum -   49 Outer drum -   50 Heating device -   51 Gas burner -   52 Heat exchanger -   53 Inflow line -   54 Return line -   55 Storage tank -   56 Feed line -   57 Outflow line -   58 Outflow line -   59 Inflow line -   60 Return line -   61 Storage tank -   62 Feed line section -   63 Feed line section -   64 Outflow line -   65 Spin dryer -   66 Drum -   67 Heating device -   68 Gas burner -   69 Heat exchanger -   70 Outer drum -   71 Inflow line -   72 Return line -   73 Storage tank -   74 Storage tank -   75 Feed line -   76 Feed line section -   77 Feed line section -   78 Inflow line -   79 Return line 

1. A method for the wet-treatment of laundry, the laundry being at least washed in a drum (12, 41, 66) which can be driven in rotation using a heated-up treatment liquid, wherein the treatment liquid is heated up by at least one heating device (26, 50, 67).
 2. The method according to claim 1, wherein the heating device (26, 50, 67) is operated with fossil fuels.
 3. The method according to claim 1, wherein the heating device (26, 50, 67) operates in the manner of a flow heater.
 4. The method according claim 1, wherein the treatment liquid that is warmed by the heating device (26, 50, 67) is pumped so as to circulate through at least one chamber (13, 42) in the drum (12, 41, 66), which can be driven in rotation.
 5. The method according to claim 1, wherein the treatment liquid that is warmed by the heating device (26, 50, 67) is pumped in a continuous circuit through at least one chamber (13, 42).
 6. The method according to claim 1, wherein the treatment liquid that is warmed by the heating device (26, 50, 67) is pumped so as to circulate through at least one chamber (13, 42) that has an outer drum (23, 24, 48).
 7. The method according to claim 1, wherein the heating device (26, 50, 67) is operated continuously.
 8. The method according to claim 1, wherein at least one burner of the respective heating device (26, 50, 67) is operated in an uninterrupted manner.
 9. The method according to claim 1, wherein operation of the heating device (26, 50, 67) is at least temporarily continued after the treatment liquid for washing the laundry is heated up.
 10. The method according to claim 1, wherein operation of the heating device (26, 50, 67) is at least temporarily continued in order to heat up the treatment liquid for washing the next batch of laundry after the treatment liquid for washing the laundry is heated up.
 11. A method for the wet-treatment of laundry, the laundry being at least washed in a drum (12, 41, 66) that can be driven in rotation using a warmed treatment liquid, wherein treatment liquid for the laundry in the drum (12, 41, 66) or for other purposes is heated up or warmed alternately by a heating device (26, 50, 67).
 12. The method according to claim 11, wherein temporarily stored treatment liquid is warmed up between successive phases of heating-up of the treatment liquid of successive batches of laundry in the drum (12, 41, 66).
 13. The method according to claim 11, wherein treatment liquid for washing the laundry in the drum (12, 41, 66) is first heated by the heating device (26, 50, 67) and, when this treatment liquid has reached an intended temperature, temporarily stored treatment liquid is warmed in at least one storage tank (31, 55, 74).
 14. The method according to claim 11, wherein treatment liquid which serves for main washing of the laundry is heated by the heating device (26, 50, 67).
 15. The method according to claim 11, wherein main-wash liquid which serves for main washing of the laundry is heated by the heating device (26, 50, 67).
 16. The method according to claim 13, wherein the warmed treatment liquid in the storage tank (31, 55, 74) is used to wash the laundry into the drum (12, 41, 66).
 17. The method according to claim 13, wherein the warmed treatment liquid in the storage tank (31, 55, 74) is used to prepare pre-heated main-wash liquid.
 18. The method according to claim 1, wherein temporarily stored treatment liquid is warmed up between successive phases of heating-up of the treatment liquid of successive batches of laundry in the drum (12, 41, 66).
 19. The method according to claim 1, wherein treatment liquid for washing the laundry in the drum (12, 41, 66) is first heated by the heating device (26, 50, 67) and, when this treatment liquid has reached an intended temperature, temporarily stored treatment liquid is warmed in at least one storage tank (31, 55, 74).
 20. The method according to claim 1, wherein treatment liquid which serves for main washing of the laundry is heated by the heating device (26, 50, 67).
 21. The method according to claim 1, wherein main-wash liquid which serves for main washing of the laundry is heated by the heating device (26, 50, 67).
 22. The method according to claim 19, wherein the warmed treatment liquid in the storage tank (31, 55, 74) is used to wash the laundry into the drum (12, 41, 66).
 23. The method according to claim 19, wherein the warmed treatment liquid in the storage tank (31, 55, 74) is used to prepare pre-heated main-wash liquid. 